"I take allergy preparations year round, Claritin in fall and winter, and Allegra spring and summer. Both claim to be effective immediately, (within hours) however, my experience is that it takes a week for them to work, so, for a week in spring, and a week in the fall, I take both, otherwise I am miserable with runny nose itchy eyes, sore throat, etc. Both claim to be non drowsy, but for me this is not the case, so I take them at night. I give allegra a middle of the road 5 as a rating, because it's better than nothing!"